The removal of some or all of the particulate material from air and gas streams over extended time periods is an often addressed need in both residential and industrial settings—e.g. air intake streams to the cabins of motorized vehicles, gas streams directed to gas turbines, HVAC air, aircraft cabin ventilation, clean room ventilation, furnaces, etc. These applications have varied particle removal needs (particle size, efficiency) and priorities. For example, high efficiency removal of sub-micron particles is needed in clean rooms and often high filter pressure drops are accepted. In HVAC air filter applications, life of the filter and hence pressure drop is of high priority. High backpressure on pumps and other equipment can result in equipment failure as well.
The “lifetime” of a filter is typically defined according to a selected limiting pressure drop across the filter. Since this buildup of pressure is a result of loading of dust particles, for systems of equal efficiency a longer life is typically directly associated with higher dust holding capacity. As such it is desirable to create a filter media that can perform for extended periods of time at a high efficiency level coupled with the ability to maintain a relatively low pressure drop. This invention allows for the design of a mechanical efficiency (no electrostatic charges) filter media containing nanofibers that has a very high efficiency (HEPA filtration levels) at a low pressure drop.